1. Field of the Invention
The present invention relates to a lithography apparatus, more particularly, to a lithography apparatus with an optical fiber module to improve the resolution of the lithography process.
2. Description of the Prior Art
Lithography process is important in transferring the circuit pattern onto the substrate. By projecting a light beam through the photo mask onto the photoresist, and then exposing, developing, and etching the substrate, the substrate which is uncovered by the photoresist is removed. In this way, the pattern can be transferred onto the remaining substrate. As the integrity of the IC increases, lithographic errors may easily happen. To correct these lithographic errors, immersion lithography is widely utilized in the semi-conductive field. Immersion lithography provides a possibility for increasing the resolution of an optical lithographic system. Immersion lithography is a technology in which lithographic exposure to be applied to a photoresist coated wafer is performed with a kind of immersion fluid, such as purified water, introduced between the projection lens of a stepper and the wafer. The wavelength of the light beam is shortened after passing through the immersion fluid, and the resolution of the lithographic exposure is therefore increased.
However, there are a few issues that need to be addressed in order for the promise of immersion lithography to materialize. For example, chemical substances such as photo acid generators (PAGs) leached from the photoresist to the wafer during exposure can adversely affect the image on the wafer. Furthermore, bubble generated in the immersion fluid may lead to patterns distortion. Moreover, the resolution of traditional immersion lithography is around 40 nm which is not good enough for the continuously shrinking trend of critical dimension.